Automotive designers have from time to time deemed it desirable to provide automobile windows with accent lines, particularly the rear window or "backlight" of an automobile. Such an accent line gives the illusion of two sheets of glass butted together, or of a much more sharply bent portion than is actually provided.
Prior to the present invention, the customary way of providing such an accent line on a pirce of glass has been to grind a groove into the glass surface prior to bending. Since such a technique entails a separate process step which adds to production costs, a different technique for providing an accent line would be desirable. Accordingly, it is an object of the present invention to create an accent line in a glass sheet simultaneously with the bending thereof.
U.S. Pat. No. 4,081,263 discloses the use of a rod or cylinder as a fulcrum for initiating the bending of a glass sheet to a sharp curvature. Such a procedure is not pertinent to the production of an accent line of the type to which the present invention pertains actual sharp bending of the glass sheet is basically different from producing an accent line. Rather, an accent line is an impression in the glass surface at a location on the glass sheet otherwise possessing a relatively gentle curvature. For these reasons, the rather substantial body of prior art relating to the production of "V-bends" in glass sheets is not pertinent to the present invention. Additional examples of such prior art V-bending techniques may be found in U.S. Pat. Nos. 3,795,570 and 3,795,501.
The following references may be pertinent to the novel aspects of the present invention. U.S. Pat. Nos. 3,421,875 and 3,477,840 disclose the use of furnace gas to heat a press bending mold. U.S. Pat. No. 3,595,636 discloses supplying a bending mold with heated gases generally. U.S. Pat. No. 3,340,037 discloses an arrangement for concentrating the impingement of heated gases onto particular portions of a glass sheet being bent within a furnace.
In copending U.S. patent application Ser. No. 26,107, filed on even date herewith by George R. Claassen and entitled "Method of Making Accent Lines in Bent Glass Sheets," there is disclosed and claimed the general concept of impressing a solid, rod-shaped object into the surface of a glass sheet during press bending of the glass sheet to produce an accent line. The present invention employs that same general concept, but is directed to a specific alternate embodiment for carrying out that concept.